avoid crashing on undetermined locations

this works around what is probably a bug in pygeoip:

    01:21:44 <@anarcat> .ip 10.0.0.1
    01:21:49 <peoplesmic> AttributeError: 'NoneType' object has no attribute 'get' (file "/usr/local/lib/python3.4/dist-packages/pygeoip/__init__.py", line 491, in country_name_by_addr)

it seems that, even internally, pygeoip doesn't handle very well
addresses that have no location defined... this patch should fix the
problem in willie until it is fixed upstream.
keep the Location tag even if unknown so display is more consistent
Merge pull request #681 from anarcat/rfc1918_geoip_crash

[IP]Don't crash on Unknown locations.